The death of the body is the inevitable outcome of the disease of aging. When assessing the dynamics of aging, two indicators are important – the average indicator and the indicator of the maximum life expectancy.
Searching for the stages of pathogenesis that limit a long and healthy life, I came to the conclusion that the indicator of the maximum or species life expectancy is associated with physiological aging (senescence) and depends on the only unique internal pathogenic factor – oxygen deficiency in organs and tissues and is determined by specific (per unit mass of body weight per unit of time) by the rate of formation of carriers of free energy: adenosine triphosphoric acid (ATP), reduced forms of nicotinamide-adenine dinucleotides (NADH, NADPH), reduced forms of flavine-adenine dinucleotide (FAD) and acetyl-coenzyme A (acetyl-CoA).[1]
Indicator of maximum life expectancy has not changed over the centuries and therefore is a species-specific feature. At the same time, the partial pressure of oxygen in different organs and tissues differs significantly, and therefore the levels of hypoxia, normoxia and hyperoxia for each organ and each tissue are unique [7].
Max Rubner first drew attention to the limitation of the maximum life span for the species of warm-blooded animals, while studying the energy characteristics of animals under resting conditions. More on this in the second part of the review.
Specific rates of synthesis of energy carriers, in turn, are determined not only by the partial pressure of oxygen in organs and tissues, but also by the specific content of mitochondria in cells, which catalyze the main process of synthesis of carriers of free energy – oxidative phosphorylation.
In a number of cells (stem, tumor) and tissues (embryonic tissue, fetus and «cambial» tissues of stem cell niches), in which aerobic glycolysis and the pentose phosphate cycle make a significant contribution to the production of free energy carriers, the amount of enzymes of these metabolic pathways present in cells also determines the specific rates of synthesis of free energy carriers.
Thus, the indicator of the maximum or species life expectancy of organisms is determined by the specific rates of synthesis of free energy carriers (per gram of tissues and organs per unit of time): ATP, NADH, NADPH, FMN, FADH